Introducing a self-improving catalyst for hydrogen evolution and efficient catalyst for oxygen evolution reaction

Abstract Herein, MoS2/Ni3S2 nano-cubic rods (NCR) is fabricated on Ni foam via a two-step process including modified solution method and thiourea phosphate-assisted strategy. The resultant material serves as a self-improving high intrinsic catalyst for hydrogen evolution reaction (HER), and exhibits desirable activity for oxygen evolution reaction (OER) in alkaline media. Results demonstrated that two different phases of MoS2 and Ni3S2 along with the presence of abundant active sulfur edge sites and particular structure lead to the enhanced electrocatalytic activity. The most interesting point is the self-improving behavior of MoS2/Ni3S2 NCR by proceeding the HER. It means by time and catalyzing the hydrogen evolution reaction the performance of catalyst improved, so that after long time HER the catalyst reaches 10 and 20 mA cm−2 at overpotential of 40 and 85 mV, respectively. It is found that the improvement in catalytic performance can be assigned to the charge transfer enhancement and increasing in active surface area as HER proceeds. Further, characterization investigations show that thiourea phosphate-assisted strategy plays a key role to attain the nano-cubic rods structure. Indeed, the generated MoS2 nanolayers act as a substrate for anchoring and growing of Ni3S2 nano-cubic particles and consequently lead to preparation of cubic nano rods structures. Besides, low onset potential with the overpotential of 200 mV was obtained for OER using MoS2/Ni3S2 NCR.